after + than a ½-century of supporting breakthrough sci work—and providing a scenic backdrop for contact, goldeneye nother blockbuster hollywood films—the iconic arecibo observatory in puerto rico is goin dark.
the u.s. national sci foundation (nsf), which owns the observatory, anncd on nov 19 that 'twill begin the process of planning for “controlled decommissioning” of the 305-mt telescope. ‘oer the past several mnths the instrument has suffered two catastrophic failures of cables that support its 900-ton (817-metric-ton) central receiving platform.
“this decision is intended to preserve life and safety of pplz and prevent the loss of the entire arecibo observatory, including the visitor education center, inna event of an unexpected and uncontrolled collapse,” said sean jones, assistant director of the directorate for mathematical and physical scis atta nsf, dur'na press conference. “this decision aint an easy one for nsf to make. but safety of pplz is our №-one priority.”
fears of life-threatening danger
ralph gaume, director of the nsf’s division of astronomical scis, says that although the telescope is bein’ decommissioned, the agency is “not closing arecibo observatory.” instead the plan is to retain as much as possible of the surrounding infrastructure in hopes that it still mite fulfill various research and educational purposes.
according to the nsf’s nov 19 statement the decision came after evaluating “multiple assessments by indie engineering companies that found the telescope structure is in danger offa catastrophic failure and its cables may no longer be capable of carrying the loads they were designed to support.” any attempts at repairs, the agency noted, “’d put workers in potentially life-threatening danger.” and even if repairs proved successful, engineers had “found that the structure ‘d likely present long-term stability issues.”
the nsf does not yet ‘ve a fully formed plan for the decommissioning, gaume says. but such a plan ‘d emerge in coming weeks, he adds, n'it ‘d rely on explosive demolition for somd' structure. at present, tis any-1’s guess as to how long the decommissioning ‘d take and at wha’ expense. an nsf estimate from 2016, however, gauged the total cost of deconstructing the observatory at tween $10.6 million and $18.7 million.
“our engineers aint able to tell us when the structure ‘d collapse on its own, and so we’re working gainsta clock,” gaume says. wrt farming out arecibo sci investigations to other observatories, he adds, “certainly some subset of the sci that is bein’ done on arecibo ‘d, potentially, transfer to other facilities and, in pticular, to other nsf facilities.” but'a observatory’s gargantuan dimensions and speshized hardware make it a one-of-a-kind resrc. for many applications in astronomy and planetary sci, thris simply no other available facility to fill the research void arecibo’s decommissioning will cutout behind.
catastrophic cable failures
without ?, the past few yrs ‘ve not been kind to arecibo. backin sep 2017 the radio telescope took a beating from hurricane maria. the observatory lost one of its catwalk floors, na fall of line feed damaged dozens of the radio dish’s + than 38,000 aluminum panels.
but those damaging blos pale in contrast to the havoc wrought by an auxiliary cable break on aug 10, folloed by a main cable failure on nov 6.
“each of the structure’s remaining cables is now supporting + w8 than b4, increasing the likelihood of another cable failure, which ‘d likely result inna collapse of the entire structure,” explained a university of central florida statement earlier this mnth. (the university manages the facility through a contract w'da nsf.) engineers ‘ve also envisaged additional signs of excess wear and tear on two of the remaining cables, creating a dynamic “industrial failure” situation that poses severe safety risks for workers.
despite these woes, francisco cordova, arecibo’s current director, had expressed cautious optimism bout the observatory’s eventual recovery in an oct 12 statement: “we continue to make progress,” he wrote, “but'a process is slo as we develop a comprehensive plan for facility repairs while prioritizing the safety of our staff…. bottom line… we're making significant progress towards restoring the operational capability of this historic facility.”
an irreplaceable resrc
built in 1963, arecibo was the realm’s largest operational single-dish radar/radio telescope til twas shuttered by the broken cables earlier this yr. scis regularly used its outsize dimensions to pull off otherwise impossible feats of telescopic derring-do, s'as constructing detailed radar maps of asteroids, comets and planets, studying the exotic physics of whirling pulsars, and even beaming detailed messages into intergalactic space as pt of the search for extraterrestrial intelligence (seti). every yr roughly 200 scis ‘ve taken advantage of arecibo’s prowess to pursue their investigations.
jill tarter, chair emeritus for seti research atta seti institute in mountain view, calif., spoke to sci american prior to the nsf’s decommissioning decision. at that time, she hailed arecibo as a one offa kind resrc, noting that even tody it still possesses the realm’s most uber planetary radar transmitter. “somd' sci can be switched to other facilities,” tarter added, although arecibo’s sensitivity is required by certain projects—s'as nanograv, which seeks to directly detect and study nanohertz-frequency gravitational waves. “i think in debating repairs versus closing it down, the cost arguments will ‘ve to include that unique capability thall be lost,” she said.
the situation is a quandary, says dan werthimer, a radio astronomer and seti researcher atta university of california, berkeley. “they don’t quite cogg how this happened, so u don’t know how to fix the facility in a safe and guaranteed way.”
like many researchers who ‘ve utilized arecibo, werthimer defends the observatory as a singular src of profound discoveries that has played a crit role in piecing together the puzzle of humankind’s place inna universe. t'has also served a vital sci-outreach role, even outside of its hollywood allure, by its contributions to seti@home. that initiative, spearheaded by werthimer, enlisted millions of volunteers donating computer time to analyze arecibo data in a global sci project seeking to answer that most daunting query: “are we alone?”
in arecibo’s absence, werthimer’s seti research will continue with ongoin collaborative work now underway at china’s newly commissioned 5-hundred-mt aperture spherical radio telescope (fast), which, as its name suggests, boasts a dish even larger than arecibo’s. “it’s a spectacular radio telescope, but it can’t do the things that arecibo does cause fast doesn’t ‘ve a transmitter,” werthimer says.
meanwhile china recently anncd tis opening up fast to other collaborators, making the telescope + readily available to researchers from other nations. this “open skies” approach tis ideal way t'get the best sci onna telescope, werthimer says.
through funding from nasa’s near-earth object (neo) observations program, arecibo has also served as 1-odda globe’s primordial assets in studying potentially hazardous neos that ‘d strike earth. thx to arecibo’s uber radar transmitter, researchers ‘ve fully toonized the precise orbits, sizes and shapes of many neos during the space rocks’ close encounters with our planet.
in a nov 19 statement reacting to the nsf decision, nasa said that its goldstone deep space communications complex in california—which also boasts a potent planetary radar—recently returned to full operations after upgrades to its high-power transmitter. cause the space agency 1-ly uses goldstone and arecibo alike for studying known neos rather than discovering new ones, the statement noted, “nasa’s neo search efforts aint impacted by the planned decommissioning.”
“tis obviously a very difficult situation for the nsf and arecibo,” says anthony beasley, director of the nsf-funded national radio astronomy observatory, which does not include arecibo in its purview. “in this kind of situation, you can’t ‘ve a whole lotta engineers crawling all ‘oer the telescope figuring out wha’’s wrong,” he says. “they ‘ve to diagnose the problem in a safe way, and that’s a'bitto a challenge.”
‘d the observatory ‘ve been saved? scis and historians will likely debate the circumstances of arecibo’s death knell for yrs to come. beasley notes one thing is indisputable, however: “arecibo is a very unique facility,” he says, “and its capabilities aint goin to be reproduced anywhere else quickly.”
original content at: rss.sciam.com…
authors: leonard david